The present invention relates in a general way to vehicle parking brakes and, more particularly, the present invention is directed to an electrofluidic parking brake control apparatus operable on a vehicle that is equipped with an electrofluidic braking system.
A rather significant number of vehicles that are in present day use are equipped with such electrofluidic type braking systems. One type of electrofluidic braking system is disclosed in my earlier filed and copending U.S. patent application bearing Ser. No. 564,655, that was filed on Dec. 23, 1983 and allowed on Mar. 15, 1985 the subject matter of which is incorporated herein by reference. It is known that an electrofluidic braking system is of particular usefulness in the railroad industry and this is especially the case with respect to the rapid transit segment of such railroad industry because of the generally smoother and more uniform braking action observed with an electrofluidic braking system.
Nevertheless, despite the popularity of the electrofluidic braking systems, one problem of considerable concern has been observed with the parking brake of such systems. The problem observed is that there has been a number of occasions when an untimely application of the parking brake has occurred. This is an undesirable situation in that when an application of the parking brake occurs and such application was not initiated by the person operating the vehicle then a number of things may happen. Unfortunately, none of the things which can occur would be considered desirable. For example, one of the things that will be experienced is added wear and tear on the vehicle braking equipment especially to the brake shoes. This in turn not only adds to the maintenance cost of the braking equipment but in addition and of even more importance the equipment is out of service during such maintenance. Furthermore, added cost will be incurred as a result of the increased wear that will likely be experienced on the metallic wheels on railway equipment or rubber tires on over-the-road type vehicles as well as to the metal rails or various types of roadway surfaces for such respective vehicles. An additional cost can also be associated with this problem due to the extra power that is required to overcome the drag on the wheels caused by the parking brake which necessitates the use of added fuel.
It may also be observed especially with respect to a rapid transit system of the rail type that numerous schedule delays may be experienced not only to the vehicle that is undergoing such untimely parking brake application but also to other vehicles which may be following on the same track. Obviously, many passengers may be unhappy over such delays and as a consequence the rapid transit system may lose future passengers and the revenue from such passengers.